1. Technical Field of the Invention
The present invention relates to the estimation and amelioration of noise in image sensor systems.
2. Description of Related Art
The outputs of image sensor systems inherently contain noise. Noise may arise from many sources, for example by the inherent physics of the image sensor device (thermal noise, Schott noise) or at the system level though interference, crosstalk, or even poor power supply routing. If the signal/noise ratio is sufficiently high the displayed image will be perceptibly degraded, for example by speckling or striping depending on the nature and origin of the noise.
Many efforts have been made over the years to address problems related to noise. One line of approach is to use digital signal processing. Many complex image processing DSP designs have been devised using fuzzy or deterministic algorithms, but cannot always be depended upon. One reason for this is that reliably differentiating between random noise and real image data has been a known problem for many years. Image processing is more likely to fail in real scenes where there is a lot of scene detail, i.e. the scene contains an amount of genuine high frequency animated information such as blades of grass or tree leaves. This detail is likely to be interpreted as noise, and the resulting processing as by smoothing or other algorithms will remove or modify essential detail and so compromise the perceived quality of the resultant image.
There is a need in the art to address these issues by providing a novel approach to assessing the “noisiness” of image signals.